Polyester fiberfill has become well accepted as an inexpensive material for pillows, other bedding articles, such as quilts and sleeping bags, apparel and furnishing cushions, and is used in large quantities commercially. The fiberfill is generally made from poly(ethylene terephthalate) fibers in staple form, of various cut lengths. Hollow fibers are sometimes used in preference to solid fibers, and use of a silicone slickener has given an improvement in lubricity and aesthetics. However, down and blends of down with feathers are still preferred by some consumers for some purposes because of their aesthetics. Hereinafter, we shall generally refer to down, although it will be understood that blends of down/feathers are often used and preferred in commercial practice. The main practical and aesthetic advantage over prior synthetic materials has been that down is refluffable. This means that a quilt containing compacted down can be returned quickly to its original soft fluffy condition simply by shaking and patting. This remains true for down quilts even after prolonged use (provided the down is not damaged by the effect of water). The pillows, even pure down may compact after prolonged use, so mixtures of down and feathers are generally used in preference. During use, eventually all prior synthetic substitutes develop gross defects, such as matting of the fiberfill, resulting in a very lumpy article, or lesser clumping of the fiberfill, which is noticeable as lack of uniformity and reduction in softness during prolonged use, as contrasted with down. What has been desirable, has been a washable article that can be repeatedly refluffed merely by shaking and patting.
Because of the commercial desirability of providing a washable down-like substitute, considerable research has been devoted to the study of down and feathers and their structures. Attempts have been made to simulate the characteristics and structure of down and of feathers using polyester fiberfill substitutes in such forms as have been referred to variously as flakes, e.g., U.S. Pat. Nos. 4,259,400 and 4,320,166, loops, e.g., GB No. 2,050,818 and pom poms, e.g. U.S. Pat. No. 4,418,103. These included several suggestions for producing substitutes for down by converting polyester fiberfill into spherical bodies.
Miller, U.S. Pat. No. 3,892,909 discloses assemblages of several shapes, including substantially cylindrical or spherical bodies and feathery bodies, of synthetic fibers for simulating down. Miller does not disclose any machines for manufacturing these bodies. Miller's process involves treating a tow or other fiber bundle with a binder, cutting the treated tow to form staple, forming the bodies of the desired shape, and drying to set binder and retain thereby the desired shape of the body. While use of a binder is considered essential by Miller, this necessarily reduces the softness of the product, and so it would be desirable to avoid the need to use binder for this purpose. Nishiumi et al., U.S. Pat. No. 4,065,599 discloses spherical objects composed of fibers of length at least 0.2 m that are similarly fixed on each other at their points of contact, by using an adhesive or a thermoplastic polymer of low melting point. Nishiumi makes each spherical object individually by jetting the fibers into a porous vessel and rotating and shearing the filaments therein by means of eccentric gas streams, and then setting and fixing the filaments. Werthaiser et al., U.S. Pat. No. 4,144,294 discloses a method of changing sheet-like segments of garnetted polyester fibers into rounded bodies. These garnetted sheets have been sprayed with a resin to connect the fibers at their points of contact. The pieces may be agitated, rolled and tumbled to aid in the formation of the rounded bodies. Maruse Kogyo GB No. 2,065,728 does not mention down, but discloses wadding in the form of balls of synethetic fibers, these balls being crimped fluffs and intertwining one another. Maruse's process comprises opening the raw fiber, blowing the opened fiber through circuitous pipes made of insulating material so as to charge the fiber with electricity and thereby form the fiber into balls, and then spraying the balls with a resin binder. Thus, these prior methods involve use of a binder to fix the fibers in their ball-shape. This use of a binder and the resulting lack of freedom of movement of the fibers is not desirable for a down-like substitute, because of the significant reduction in softness that is caused thereby.
We are aware of a competitive offering (referred to as 38K) comprising some small (average dimension about 0.1 m or less) flattened discs mixed with longer cylindrical shapes (referred to herein as tails). The polyester fibers of this product have a spiral-crimp. No binder is present. 38K is an improvement on some forms of loose fiberfill with regard to refluffability, but does not compare well with down because 38K clumps during prolonged use.
Thus, no synthetic product so far has provided a real alternative to down, which has a significant advantage in refluffability. It would be desirable, therefore, to provide a polyester fiberfill with refluffable characteristics (available from down), and also with washability (unlike down) and at a lower cost than down.